A technology of peer to server and peer (P2SP) utilizes a third-party server and a data source of a peer-to-peer (P2P) network, so that a download process does not merely rely on a source server of internet service provider (ISP). Data may be transferred either between various terminals in the network or between a terminal and a server. Compared with a traditional download method of peer to server (P2S) or P2P and so on, download stability and download speeds of P2SP has been greatly improved.
In the P2SP technology, because the data comes from different data sources, in order to guarantee accuracy of a download result, each data fragment needs to be validated by fragment validation information provided by the source server. When there is an error in the validation result, client end only selects to perform the download from the source server, and gives up multisource downloading from other nodes. However, the data source provided by the source server may go wrong. Take content delivery network (CDN) as an example, it can be the case that content distribution of each node is non-synchronous or cache content is not updated in time. In the above case, even though a user downloads data from the source server, a data fragment cannot be downloaded correctly, which may lead to an issue that an entire file is still unable to be downloaded completely.